Electronic devices, such as smart phones, tablet devices, laptop and desk top computers, digital media players, and so forth, increasingly employ optical devices to control the manipulation of a variety of functions provided by the device. For example, light sensors are commonly used by electronic devices to detect ambient lighting conditions in order to control the brightness of the device's display screen and the keyboard. Typical optical devices utilize sensors that employ photodetectors such as photodiodes, phototransistors, or the like, which convert received light into an electrical signal (e.g., a current or voltage, analog or digital).
Optical devices are commonly used in gesture or proximity sensing. Gesture sensing enables the detection of physical movement largely parallel to the display surface (e.g., “gestures”) without the user actually touching the device within which the gesture sensing device resides. Proximity sensing enables the detection of physical movement that is largely perpendicular to the display surface (e.g., proximate to the display surface). The detected movements can be subsequently used as input command for the device. In implementations, the electronic device is programmed to recognize distinct non-contact hand motions, such as left-to-right, right-to-left, up-to-down, down-to-up, in-to-out, out-to-in, and so forth. Gesture and proximity sensing have found popular use in handheld electronic devices such as tablet computing devices and smart phones, as well as other portable electronic devices such as laptop computers, video game consoles, and so forth.